queries google maps to tabulate driving distances.

driving.jl

#drivingtaxes.jl

using JSON

#make sure we have what we're looking for.
(length(ARGS) == 0) && throw(ErrorException("needs a file name"))
###################################
#rows iterator
type rows; tgt::Matrix; end
Base.start(r::rows) = 1
Base.next(r::rows, idx) = (r.tgt[idx, :], idx + 1)
Base.done(r::rows, idx) = idx > size(r.tgt, 1)
Base.length(r::rows) = size(r.tgt,1)
###################################

api_key = #insert API KEY HERE

#set up a dictionary of locations.
location_dict = Dict{Symbol, String}()
known_distances = Dict{Tuple{Symbol, Symbol}, Float64}()

addresses = readcsv("Addresses.csv")
for row in rows(addresses)
  location_dict[Symbol(row[1])] = row[2]
end

function api_lookup(strt_loc, dest_loc)
  strt_addr = replace(location_dict[strt_loc],r"\s","+")
  dest_addr = replace(location_dict[dest_loc],r"\s","+")
  query = string("https://maps.googleapis.com/maps/api/distancematrix/json?units=imperial&origins=",strt_addr,"&destinations=",dest_addr,"&key=",api_key)

  cr = readstring(`curl $query`)
  j = JSON.parse(cr)

  try
    Float64(parse(split(j["rows"][1]["elements"][1]["distance"]["text"])[1]))
  catch
    return -1.0
  end
end

function lookup_distance(strt_loc, dest_loc)
  if haskey(known_distances, (strt_loc, dest_loc))
    known_distances[(strt_loc, dest_loc)]
  else
    #actually do API stuff here.

    distance = api_lookup(strt_loc, dest_loc)
    #distance = 1.0
    known_distances[(strt_loc, dest_loc)] = distance
  end
end

list_filename = ARGS[1]
listtbl = readcsv(list_filename)
output_tbl = Array{Any, 2}()
for row in rows(listtbl[:,1:3])
  if row[1] == "Date"
    output_tbl = hcat(row', "")
  else
    strt_loc = Symbol(row[2])
    dest_loc = Symbol(row[3])

    haskey(location_dict, strt_loc) || throw(ErrorException("key for $strt_loc not found"))
    haskey(location_dict, dest_loc) || throw(ErrorException("key for $dest_loc not found"))

    #first check to see if the distance exists.
    output_tbl = vcat(output_tbl, hcat(row', lookup_distance(strt_loc, dest_loc)))
  end
end

writecsv(string("final_", list_filename), output_tbl)